128 
SEEILAND 
feet, and fully 5 out of the 7 J miles of the low eliff reveal the sub- 
stratum of planed granite beneath a torrential veneer, while there 
is more of alluvium-free granite than of graniteless alluvium. 
The sharp contrast between mountain and plain is doubtless due 
to the character of the scant rainfall; but the relation need not 
he further pursued at present. Hardly less striking than this 
general topographic relation are the strong local features of the 
topography. Tiburon island is but 30 miles long and less than 
20 wide, yet it contains several ranges, the dominant one (Sierra 
Kunkaak) of Alpine ruggedness throughout most of its 4,000 feet 
of altitude. Sierra Seri is an imposing assemblage of peaks, 
aretes, precipices, and profound gorges, cutting the azure at fully 
5,000 feet, though the width of the range from strait to desert is 
but 10 miles. Even more impressive than the mountains, to the 
explorer on the ground, is Desierto Encinas — the broad waste of 
playas and sand dunes lying over against the Papago of old, the 
law-bound Sonora of today. Toward its broad basin-shape ex- 
panse storm freshets flow apparently from all directions, yet it 
is never filled and rarely wetted, and the scant water sometimes 
rising to the surface on its steeper western slope is saline ; it is 
partly barred from the gulf and lined in its lower levels by a 
sheet of sediment charged with recent marine shells, which show 
that at no remote day it was an arm of the sea. Of interest, too, 
is the gale-swept strait El Infiernillo, for the foot-slo})es on island 
and mainland are just such as sweep down and merge between 
the parallel ranges of the interior, and extend nearly or quite to 
the coastline where they are cut by wave-carved cliffs or pass 
into current-built sand-spits, making 'it manifest that the strait 
was original!}^ a subaerial valley like those of the interior and 
onl}" recently occupied and slightly modified by the sea. Isla 
Tassne, too, is a noteworthy feature ; though but a fraction of a 
mile in any dimension and for the most part a wave-built bench, 
its nucleus is a 500-foot spire of rock, the half-submerged crest 
of a twinned peak, on which myriads of water fowl nest. The 
topographic detail of Seriland is that of water-carving or water- 
building, yet the aridity is such that the work must proceed 
at infinitesimal rate. The dearth of water is a burning ques- 
tion to the explorer, a vital element in prospective conquest of 
Seriland for the behoof of civilized man. In all the half dozen 
valle3''S, the hundred barrancas, and the thousand storm-cut 
gorges, there are probably less than a dozen nominally perma- 
nent, and but two or three actually permanent, sources of fresh 
water in the territory. 
